Resource allocation in a wireless network

ABSTRACT

A control message prospectively indicates a need of a communication device sending a data packet of a first class of data employing radio resources. The radio resources are reserved at least for the first class of data.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/003,852, filed on Jan. 22, 2016, which itself is a continuation ofPCT International Application No. PCT/EP2015/051337, filed on Jan. 23,2015, the disclosure and content of each of which are incorporatedherein by reference herein in their entireties.

TECHNICAL FIELD

Various embodiments relate to a communication device, to an access nodeof a wireless network, and to a system. In particular, varioustechniques relate to resource allocation in a wireless network. A needfor sending of a data packet of a first class of data employing radioresources which are reserved at least for the first class of data issignalled.

BACKGROUND

Wireless network technologies exists which are employed in industrialapplications. One example technology is WirelessHART, as specified byIEEE 802.15.4-2006 of the Institute of Electrical and ElectronicsEngineers. A further example, is ISA100.11a “Wireless Systems forIndustrial Automation: Process Control and Related Applications” of theInternational Society of Automation (ISA).

Such existing technologies suffer from certain limitations. E.g., it maynot be possible or only possible to a limited degree to provide, both, ahigh reliability of transmission as well as a low latency oftransmission. In particular, in scenarios where it is required toaccommodate multiple classes of data with different priorities fortransmission, such existing techniques may face certain restrictions anddrawbacks in terms of transmission reliability and transmission latency.

SUMMARY

Therefore, a need exists to provide techniques which alleviate at leastsome of the above-mentioned limitations and drawbacks. This need is metby the features of the independent claims. The dependent claims defineembodiments.

According to various embodiments, a communication device is provided.The communication device comprises a wireless interface. The wirelessinterface is configured to transceive data on a channel of a wirelessnetwork. The communication device further comprises a memory. The memoryis configured to store information indicating radio resources on thechannel. The radio resources are reserved for a first class of data andfor a second class of data. The radio resources are shared between thecommunication device and the further communication device. Thecommunication device further comprises at least one processor. The atleast one processor is configured to receive, via the wirelessinterface, a control message. The control message prospectivelyindicates a time-frequency resource block of the radio resources. Thecontrol message further prompts the communication device to mutetransmission in the indicated time-frequency block of the radioresources on the channel. The at least one processor is configured toretrieve the stored information from the memory. The at least oneprocessor is further configured to control the wireless interface tomute transmission in the indicated time-frequency resource block of theradio resources on the channel in response to said receiving of thecontrol message.

According to various embodiments, a communication device is provided.The communication device comprises a wireless interface. The wirelessinterface is configured to transceive data on a channel of a wirelessnetwork. The communication device further comprises a memory. The memoryis configured to store information. The information indicates firstradio resources on a channel. The first radio resources are reserved fora first class of data. The information further indicates second radioresources on the channel. The second radio resources are reserved for asecond class of data. The first radio resources are shared between thecommunication device and the further communication device. Thecommunication device further comprises at least one processor. The atleast one processor is configured to retrieve the stored informationfrom the memory and to select between the first radio resources and thesecond radio resources for sending of a data packet of the second classof data. Said selecting depends on a traffic load on a channel in thesecond radio resources. The at least one processor is configured tosend, via the wireless interface on the channel, the data packet of thesecond class of data employing the first radio resources if the firstradio resources are selected.

According to various embodiments, a method is provided. The methodcomprises a memory storing information indicating radio resources on achannel of a wireless network. The radio resources are reserved for afirst class of data and for a second class of data. The radio resourcesare shared between a communication device and a further communicationdevice. The method further comprises at least one processor receiving,via a wireless interface, a control message. The control messageprospectively indicates a time-frequency resource block of the radioresources. The control message further prompts the communication deviceto mute transmission in the indicated time-frequency resource block onthe channel. The method further comprises the at least one processorretrieving the stored information from the memory. The method furthercomprises the at least one processor controlling the wireless interfaceto mute transmission in the indicated time-frequency resource block onthe channel in response to said receiving of the control message.

According to various embodiments, a method is provided. The methodcomprises a memory storing information. The information indicates firstradio resources on a channel of a wireless network. The first radioresources are reserved for a first class of data. The informationfurther indicates second radio resources on the channel. The secondradio resources are reserved for a second class of data. The first radioresources are shared between a communication device and a furthercommunication device. The method further comprises at least oneprocessor retrieving the stored information from the memory andselecting between the first radio resources and the second radioresources for sending of a data packet of the second class of data. Saidselecting depends on a traffic load on the channel in the second radioresources. The method further comprises the at least one processorsending, via the wireless interface on the channel, the data packets ofthe second class of data employing the first radio resources if thefirst radio resources are selected.

According to various embodiments, a communication device is provided.The communication device comprises a wireless interface. The wirelessinterface is configured to transceive data on a channel of a wirelessnetwork. The communication device further comprises a memory. The memoryis configured to store information indicating radio resources on achannel. The radio resources are reserved at least for a first class ofdata. The radio resources are shared between the communication deviceand the further communication device. The communication device furthercomprises at least one processor. The at least one processor isconfigured to send, via the wireless interface, a control message. Thecontrol message prospectively indicates a need of sending a data packetof the first class of data employing the radio resources. The at leastone processor is further configured to send, via the wireless interfaceon the channel, the data packet of the first class of data employing theradio resources.

According to various embodiments, a method is provided. The methodcomprises a memory storing information indicating radio resources on achannel of a wireless network. The radio resources are reserved at leastfor a first class of data. The radio resources are shared between thecommunication device and the further communication device. The methodfurther comprises at least one processor sending, via the wirelessinterface, a control message. The control message prospectivelyindicates a need of the communication device sending a data packet of afirst class of data employing the radio resources. The method furthercomprises the at least one processor sending, via the wireless interfaceon the channel, the data packet of a first class of data employing theradio resources.

According to various embodiments, an access node of a wireless networkis provided. The access node comprises a wireless interface. Thewireless interface is configured to transceive data on a channel of thewireless network. The access node further comprises at least oneprocessor configured to prospectively allocate, on the channel in ashared manner, radio resources. The radio resources are reserved atleast for a first class of data to the communication device and to thefurther communication device. The at least one processor is furtherconfigured to receive, via the wireless interface from the communicationdevice, a control message. The control message prospectively indicates aneed of the communication device sending a data packet of the firstclass of data employing the radio resources. The at least one processoris configured to select a time-frequency resource block of the radioresources for said sending of the data packets of the first class ofdata by the communication device. The at least one processor is furtherconfigured to send, via the wireless interface to the communicationdevice and to the further communication device, a further controlmessage. The further control message indicates the selectedtime-frequency resource block of the radio resources. A further controlmessage prompts the further communication device to mute transmission inthe time-frequency resource of the radio resources on the channel. Thefurther control message prompts the communication device to send thedata packets of the first class of data employing the time-frequencyresource block of the radio resources on the channel.

According to various embodiments, a method is provided. The methodcomprises at least one processor prospectively allocating, on a channelof the wireless network and in a shared manner, radio resources. Theradio resources are reserved at least for a first class of data to acommunication device and to a further communication device. The methodfurther comprises the at least one processor receiving, via a wirelessinterface from the communication device, a control message. The controlmessage prospectively indicates a need of the communication devicesending a data packet of the first class of data employing the radioresources. The method further comprises the at least one processorselecting a time-frequency resource block of the radio resources forsaid sending of the data packet of the first class of data by thecommunication device. The method further comprises the at least oneprocessor sending, via the wireless interface to the communicationdevice and to the further communication device, a further controlmessage. The further control message indicates the selectedtime-frequency resource block of the radio resources. The furthercontrol message prompts the further communication device to mutetransmission in a time-frequency resource block on the radio resourceson the channel. The further control message further prompts thecommunication device to send the data packet of the first class of dataemploying the time-frequency resource block of the radio resources onthe channel.

According to various embodiments, a system is provided. The systemcomprises a first communication device and a second communicationdevice. The first communication device comprises a wireless interfaceand a memory and at least one processor. The wireless interface of thefirst communication device is configured to transceive data on a channelof a wireless network. The memory of the first communication device isconfigured to store information indicating first radio resources on thechannel and further indicating second radio resources on the channel.The first radio resources are reserved for a first class of data. Thesecond radio resources are reserved for a second class of data. Thefirst radio resources are shared between the first communication deviceand the second communication device. The second communication devicecomprises a wireless interface and a memory and at least one processor.The wireless interface of the second communication device is configuredto transceive data on the channel of a wireless network. The memory ofthe second communication device is configured to store informationindicating the first radio resources. The at least one processor of thesecond communication device is configured to send, via the wirelessinterface of the second communication device, a control message. Thecontrol message prospectively indicates a need of sending a data packetof the first class of data employing the first radio resources. Thecontrol message further prompts the first communication device to mutetransmission in the indicated time-frequency resource block of the firstradio resources on the channel. The at least one processor of the firstcommunication device is configured to receive, via the wirelessinterface of the first communication device on a channel, the controlmessage. The at least one processor of the first communication device isfurther configured to select between the first radio resources and thesecond radio resources for said sending of the data packet of the secondclass of data depending on a traffic load on the channel in the secondradio resources and further depending on the indicated time-frequencyresource block of the first radio resources. The at least one processorof the first communication device is further configured to control thewireless interface to mute transmission in the indicated time-frequencyresource block of the first radio resources on the channel in responseto said receiving of the control message. The at least one processor ofthe first communication device is configured to send, via the wirelessinterface on the channel, the data packet of the second class of dataemploying the first radio resources if the first radio resources areselected. The at least one processor of the second communication deviceis further configured to send, via the wireless interface on thechannel, the data packet of a first class of data employing the firstclass of radio resources.

According to various embodiments, a computer program product isprovided. The computer program product comprises program code to beexecuted by at least one processor of a network device of a wirelessnetwork, wherein execution of the program code causes the at least oneprocessor execute a method comprising controlling a memory to storeinformation indicating radio resources on a channel of a wirelessnetwork. The radio resources are reserved for a first class of data andfor a second class of data. The radio resources are shared between acommunication device and a further communication device. The methodfurther comprises the at least one processor receiving, via a wirelessinterface, a control message. The control message prospectivelyindicates a time-frequency resource block of the radio resources. Thecontrol message further prompts the communication device to mutetransmission in the indicated time-frequency resource block on thechannel. The method further comprises the at least one processorretrieving the stored information from the memory. The method furthercomprises the at least one processor controlling the wireless interfaceto mute transmission in the indicated time-frequency resource block onthe channel in response to said receiving of the control message.

According to various embodiments, a computer program product isprovided. The computer program product comprises program code to beexecuted by at least one processor of a network device of a wirelessnetwork, wherein execution of the program code causes the at least oneprocessor execute a method comprising controlling a memory to storeinformation. The information indicates first radio resources on achannel of a wireless network. The first radio resources are reservedfor a first class of data. The information further indicates secondradio resources on the channel. The second radio resources are reservedfor a second class of data. The first radio resources are shared betweena communication device and a further communication device. The methodfurther comprises the at least one processor retrieving the storedinformation from the memory and selecting between the first radioresources and the second radio resources for sending of a data packet ofthe second class of data. Said selecting depends on a traffic load onthe channel in the second radio resources. The method further comprisesthe at least one processor sending, via the wireless interface on thechannel, the data packets of the second class of data employing thefirst radio resources if the first radio resources are selected.

According to various embodiments, a computer program product isprovided. The computer program product comprises program code to beexecuted by at least one processor of a network device of a wirelessnetwork, wherein execution of the program code causes the at least oneprocessor execute a method comprising the at least one processorprospectively allocating, on a channel of the wireless network and in ashared manner, radio resources. The radio resources are reserved atleast for a first class of data to a communication device and to afurther communication device. The method further comprises the at leastone processor receiving, via a wireless interface from the communicationdevice, a control message. The control message prospectively indicates aneed of the communication device sending a data packet of the firstclass of data employing the radio resources. The method furthercomprises the at least one processor selecting a time-frequency resourceblock of the radio resources for said sending of the data packet of thefirst class of data by the communication device. The method furthercomprises the at least one processor sending, via the wireless interfaceto the communication device and to the further communication device, afurther control message. The further control message indicates theselected time-frequency resource block of the radio resources. Thefurther control message prompts the further communication device to mutetransmission in a time-frequency resource block on the radio resourceson the channel. The further control message further prompts thecommunication device to send the data packet of the first class of dataemploying the time-frequency resource block of the radio resources onthe channel.

According to various embodiments, a computer readable storage medium isprovided. The computer readable storage medium comprises program code tobe executed by at least one processor of a network device of a wirelessnetwork, wherein execution of the program code causes the at least oneprocessor execute a method comprising controlling a memory to storeinformation indicating radio resources on a channel of a wirelessnetwork. The radio resources are reserved for a first class of data andfor a second class of data. The radio resources are shared between acommunication device and a further communication device. The methodfurther comprises the at least one processor receiving, via a wirelessinterface, a control message. The control message prospectivelyindicates a time-frequency resource block of the radio resources. Thecontrol message further prompts the communication device to mutetransmission in the indicated time-frequency resource block on thechannel. The method further comprises the at least one processorretrieving the stored information from the memory. The method furthercomprises the at least one processor controlling the wireless interfaceto mute transmission in the indicated time-frequency resource block onthe channel in response to said receiving of the control message.

According to various embodiments, a computer readable storage medium isprovided. The computer readable storage medium comprises program code tobe executed by at least one processor of a network device of a wirelessnetwork, wherein execution of the program code causes the at least oneprocessor execute a method comprising controlling a memory to storeinformation. The information indicates first radio resources on achannel of a wireless network. The first radio resources are reservedfor a first class of data. The information further indicates secondradio resources on the channel. The second radio resources are reservedfor a second class of data. The first radio resources are shared betweena communication device and a further communication device. The methodfurther comprises the at least one processor retrieving the storedinformation from the memory and selecting between the first radioresources and the second radio resources for sending of a data packet ofthe second class of data. Said selecting depends on a traffic load onthe channel in the second radio resources. The method further comprisesthe at least one processor sending, via the wireless interface on thechannel, the data packets of the second class of data employing thefirst radio resources if the first radio resources are selected.

According to various embodiments, a computer readable storage medium isprovided. The computer readable storage medium comprises program code tobe executed by at least one processor of a network device of a wirelessnetwork, wherein execution of the program code causes the at least oneprocessor execute a method comprising the at least one processorprospectively allocating, on a channel of the wireless network and in ashared manner, radio resources. The radio resources are reserved atleast for a first class of data to a communication device and to afurther communication device. The method further comprises the at leastone processor receiving, via a wireless interface from the communicationdevice, a control message. The control message prospectively indicates aneed of the communication device sending a data packet of the firstclass of data employing the radio resources. The method furthercomprises the at least one processor selecting a time-frequency resourceblock of the radio resources for said sending of the data packet of thefirst class of data by the communication device. The method furthercomprises the at least one processor sending, via the wireless interfaceto the communication device and to the further communication device, afurther control message. The further control message indicates theselected time-frequency resource block of the radio resources. Thefurther control message prompts the further communication device to mutetransmission in a time-frequency resource block on the radio resourceson the channel. The further control message further prompts thecommunication device to send the data packet of the first class of dataemploying the time-frequency resource block of the radio resources onthe channel.

It is to be understood that the features mentioned above and featuresyet to be explained below can be used not only in the respectivecombinations indicated, but also in other combinations or in isolation,without departing from the scope of the present invention. Features ofthe above-mentioned aspects and embodiments may be combined with eachother in other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and effects of the invention willbecome apparent from the following detailed description when read inconjunction with the accompanying drawings, in which like referencenumerals refer to like elements.

FIG. 1 is an illustration of a critical machine-type communicationnetwork supporting transmission of a first class of data, i.e.,event-triggered data, and transmission of a second class of data, i.e.,best-effort data, via a unicast transmission and/or a broadcasttransmission on a channel according to various embodiments, the criticalmachine-type network comprising an access node and a plurality ofcommunication devices.

FIG. 2 is a schematic representation of first radio resources and secondradio resources reserved on the channel for the event-triggered data andthe best-effort data, respectively, according to various embodiments.

FIG. 3 is a schematic representation of radio resources reserved on thechannel at least for the event-triggered data and optionally for thebest-effort data according to various embodiments.

FIG. 4 is a signalling diagram of sending of a data packet of theevent-triggered data from one of the communication devices to the accessnode via the unicast transmission according to various embodiments.

FIG. 5 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources and of sending of a data packet of the best-effort datavia the broadcast transmission employing the first radio resourcesaccording to various embodiments.

FIG. 6 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources and sending of a data packet of the best-effort data viathe broadcast transmission employing the first radio resources accordingto various embodiments.

FIG. 7 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources and of sending of a data packet of the best-effort datavia the broadcast transmission employing the first radio resourcesaccording to various embodiments.

FIG. 8 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources and of sending of a data packet of the best-effort datavia the broadcast transmission employing the first radio resourcesaccording to various embodiments.

FIG. 9 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources and of sending of a data packet of the best-effort datavia the broadcast transmission employing the first radio resourcesaccording to various embodiments.

FIG. 10 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources according to various embodiments.

FIG. 11 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources according to various embodiments.

FIG. 12 is a signalling diagram of sending of a data packet of theevent-triggered data via the broadcast transmission employing the firstradio resources according to various embodiments.

FIG. 13 is a flowchart of a method according to various embodiments.

FIG. 14 is a flowchart of a method according to various embodiments.

FIG. 15 is a flowchart of a method according to various embodiments.

FIG. 16 is a flowchart of a method according to various embodiments.

FIG. 17 schematically illustrates the communication device according tovarious embodiments.

FIG. 18 schematically illustrates the access node according to variousembodiments.

FIG. 19 is a flowchart of a method according to various embodiments.

FIG. 20 is a flowchart of a method according to various embodiments.

FIG. 21 schematically illustrates control messages according to variousembodiments.

FIG. 22 schematically illustrates control messages according to variousembodiments.

DETAILED DESCRIPTION

In the following, embodiments of the invention will be described indetail with reference to the accompanying drawings. It is to beunderstood that the following description of embodiments is not to betaken in a limiting sense. The scope of the invention is not intended tobe limited by the embodiments described hereinafter or by the drawings,which are taken to be illustrative only.

The drawings are to be regarded as being schematic representations andelements illustrated in the drawings are not necessarily shown to scale.Rather, the various elements are represented such that their functionand general purpose become apparent to a person skilled in the art. Anyconnection or coupling between functional blocks, devices, components,or other physical or functional units shown in the drawings or describedherein may also be implemented by an indirect connection or coupling. Acoupling between components may also be established over a wirelessconnection. Functional blocks may be implemented in hardware, firmware,software, or a combination thereof.

Hereinafter, techniques are illustrated which enable to transmit datatraffic of a first class of data and traffic of a second class of dataemploying radio resources. Generally, the radio resources may be sharedbetween a first communication device and a second communication deviceand/or further communication devices (shared radio resources). Thus, thechannel may be shared between the communication devices. The first classof data may have a higher transmission priority than the second class ofdata. The transmission priority may be defined in the framework of aQuality of Service (QoS); thus, generally, QoS requirements may bestricter for the first class of data than the second class of data. Thetechniques allow achieving reliable transmission while, at the sametime, enabling low-latency transmission. Hence, a likelihood of lostdata packets may be comparably low.

According to various scenarios, the need of signalling a data packet ofthe first class of data is prospectively indicated. This signalling maybe implemented even though radio resources on the channel may beavailable to the sending entity which radio resources are reserved forthe first class of data. This allows re-using the radio resourcesreserved at least for the first class of data for transmission of datapackets of other classes of data, e.g., of a second class of data. Inparticular, re-using may be possible in a situation where no data packetof the first class of data has been indicated; at the same time, if thedata packet of the first class of data has to be transmitted, i.e., whenthere is a need of transmitting the data packet of the first class ofdata, collision with data packets of the second class of data may beavoided by the prospectively indicating. Also, collision with other datapackets of the first class of data, e.g., sent by other sendingentities, may be avoided. Thus, the prospectively indicating allowsother devices to become pre-emptively aware of the presence of the datapacket of the first class of data and block or mute their transmissions.

Generally, such techniques as illustrated above and illustrated below atgreater detail may find application in various network technologies,e.g., according to the Third Generation Partnership (3GPP) Long TermEvolution (LTE) radio access technology. In some scenarios, suchtechniques may be applied in critical machine-type communication (MTC)networks.

In FIG. 1, an MTC network 100 is shown. The MTC network 100 comprisescommunication devices (UEs) 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2and an access node 102. The access node 102 centrally establishes acell. The MTC network 100 may also be referred to as a centralizedsystem for industrial automation as the MTC network 100, in the scenarioof FIG. 1, comprises a single centre-excited cell. The size of the cellmay correspond to around 50-250 meters, preferably approximately 100meters.

The MTC network 100 of FIG. 1 relies on the 3GPP LTE radio accesstechnology or a modification thereof. While hereinafter reference willbe primarily made to scenarios relying on the 3GPP LTE radio accesstechnology, it is also possible that other radio access technologies areemployed, e.g., the Universal Mobile Telecommunications System (UMTS)radio access technology as specified by the 3GPP. As mentioned above, itis, in particular, possible to employ the techniques for certainenhancements of the LTE radio access technology; e.g., a transmissiontime interval or orthogonal frequency-division multiplexing symbollength may be scaled down in the access technologies applied accordingto various embodiments—e.g., if compared to the LTE radio accesstechnology, by a factor of five or ten.

From FIG. 1 it can be seen that the MTC network 100 supports, both,broadcast transmission 180 (shown in FIG. 1 with the full line), as wellas unicast transmission 190 (shown in FIG. 1 with the dashed line).Broadcast transmission 180 relates to point-to-multipoint transmission;while unicast transmission 190 relates to point-to-point transmission.The broadcast transmission 180 is typically directed to all otherdevices forming the MTC network 100; however, it is also possible thatthe broadcast transmission 180 is directed to a subset of all devicesforming the MTC network 100.

For the unicast transmission 190 and/or the broadcast transmission 180at least of payload data, the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2 and the access node 102 may share a channel of the MTC network100. The channel may comprise time-frequency resource blocks that aredefined in time and/or frequency. Generally, the channel may be anuplink (UL) channel. In case of the 3GPP LTE radio access technology,the channel may correspond to the Physical UL Shared Channel (PUSCH)which is employed for transmitting user-plane data or payload data ofhigher layer protocols.

For the unicast transmission 190 and/or the broadcast transmission 180of control messages, the MTC network 100 may provide at least onededicated control channel. The control channel may be uniquely allocatedto each one of the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2.Thereby, collisions between different UEs 101 a-1, 101 a-2, 101 a-3, 101b-1, 101 b-2 sending control messages may be avoided. However, it isalternatively or additionally also possible that a control channel isimplemented which comprises shared radio resources allocated to morethan one UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2; in particularin such a scenario, the broadcast transmission 180 may be employed.

To reduce a likelihood of collisions, radio resources on the channel maybe reserved for certain classes of data, e.g., distinctly to a specificclass of data or to more than one class of data. Radio resources may bedefined as a set of time-frequency resource blocks. Reserving radioresources may correspond to a technique where, at some point in time,radio resources are reserved for a future period of time. Generally, itis possible that the reserved radio resources are reoccurring, i.e.,from time-to-time during the future time period there may bereoccurrences of the reserved radio resources. In any case, the radioresources may be shared radio resources.

The access node 102 acts as a central network manager of the MTC network100. The access node 102 is configured to receive sensor data fromsensors and to transmit the sensor data to actuators; the sensors andactuators are implemented by or coupled to the UEs 101 a-1, 101 a-2, 101a-3, 101 b-1, 101 b-2. Therefore, the access node 102 may be consideredto be one-to-one attached to the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2 which may be also referred to as programmable logic device(PLC). The number of UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2shown in FIG. 1 is five; however, generally, there may be a largernumber of UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 connected tothe MTC network 100, e.g., approximately thirty. There may be more thanone access node 102.

The MTC network 100 may impose comparably strict requirements in termson reliability and delay, respectively latency, on the transmission 180,190 of data. In particular, in the MTC network 100 according to FIG. 1,support for coexistence between the first class of data and the secondclass of data is provided.

E.g., the first class of data may be event-triggered data; the secondclass of data may be best-effort data. Hereinafter, reference will bemade primarily to the first class of data as event-triggered data and tothe second class of data as best-effort data; however, generally, it ispossible that the first and second classes of data correspond todifferent types or kinds of data.

The best-effort data and/or the event-triggered data may be sent fromthe UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 to the access node102 in an UL transmission and/or to remaining UEs 101 a-1, 101 a-2, 101a-3, 101 b-1, 101 b-2 in a device-to-device (D2D) transmission.Typically, the event-triggered data and/or the best-effort data is sentvia the unicast transmission 190 from a given UE 101 a-1, 101 a-2, 101a-3, 101 b-1, 101 b-2 to the access node 102.

The event-triggered data may correspond to high-priority data—inparticular if compared to the best-effort data. E.g., a QoS requirementof latency and/or priority may be stricter for the event triggered datathan for the best-effort data. The event-triggered data may correspondto exceptional messages, sporadic messages such as emergency messages orthe like, etc. The event-triggered data may be triggered by an event,e.g., by an exceptional or unforeseeable event. In FIG. 1, the UEs 101a-1, 101 a-2, 101 a-3 are capable of sending the event-triggered data.

The best-effort data may be associated with reoccurring traffic; inparticular, the best-effort data may be periodically reoccurring, e.g.,at a given periodicity or distribution of periodicities This is whysometimes the best-effort data is also referred to as periodic data.Such best-effort data may correspond to status updates, measurementvalues periodically indicated, etc. In FIG. 1, the UEs 101 b-1, 101 b-2are capable of sending the best-effort traffic. In particular, the UEs101 b-1, 101 b-2 are configured to send, in a reoccurring manner, thebest-effort traffic. In the scenario of FIG. 1, the UEs 101 b-1, 101 b-2are actuators and sensors of the MTC network 100.

Generally, it is possible that the communications devices 101 a-1, 101a-2, 101 a-3, 101 b-1, 101 b-2 are capable of sending best-effort dataand/or event-triggered data. In particular, in the scenario of FIG. 1,the UE 101 a-1 is capable of sending, both, best-effort andevent-triggered data.

In various scenarios, it is possible to define groups of UEs 101 a-1,101 a-2, 101 a-3, 101 b-1, 101 b-2 sharing resources on the channeldepending on a capability of sending the event-triggered data and thebest-effort data as indicated by the UEs 101 a-1, 101 a-2, 101 a-3, 101b-1, 101 b-2 in a capability control message. Here, it is possible togroup such UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 which havediffering capabilities in terms of sending best-effort data andevent-triggered data. E.g., it is possible to group such UEs 101 a-1,101 a-2, 101 a-3, 101 b-1, 101 b-2 that are not capable of sendingevent-triggered data with such UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2 that are capable of sending event-triggered data. UEs 101 a-1,101 a-2, 101 a-3, 101 b-1, 101 b-2 of a group may be configured to shareresources on the channel reserved at least for the event-triggered data.In particular, UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 of agroup may be configured to re-use the resources on the channel reservedat least for the event-triggered data for sending of data packets of thebest-effort data. The grouping UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2 and/or the allocation of the radio resources may be executed bythe access node 102. Such techniques of grouping allow reducing thelatency of transmission while preserving a low likelihood of collisions,as will be explained in greater detail hereinafter.

The capability control message may be sent via the unicast transmission190 and/or the broadcast transmission 180. The channel may be employedfor transmission; alternatively or additionally, the control channel maybe employed for transmission of the capability control message.

According to reference implementations such as wirelessHART andISA100.11.a, the coexistence of the best-effort data and event-triggereddata is handled in a way that does not fulfil strict latencyrequirements. Namely, such techniques according to referenceimplementations are typically based on IEEE 802.15.4-2006 and employ aframe-based approach: Here, data transmission relies on a time-series oftransmission frames. In the reference implementations, typically eachframe is sub-divided in two phases, a contention free phase and acontention based phase. Then, according to the referenceimplementations, the best-effort data is scheduled in the contentionfree phase where scheduling is assisted by a network manager; theevent-triggered data is scheduled in the contention based phase. Thereis no priority in transmission for event-triggered data over best-effortdata. E.g., in the reference implementations the following scenario mayoccur: where an event-triggered emergency message is generated duringthe contention free phase or transmission of the emergency message failsduring the contention based phase, (re-)transmission is delayed untilthe next contention-based period or the next frame, respectively. Thus,latency is comparably high.

Below, techniques according to various embodiments are describedwhich—at least if compared to the above-mentioned scenario—allow toreduce the latency in particular for transmission of the event-triggereddata while, at the same time, a high transmission reliability may beachieved. The techniques as described below allow implementing datatransmission having a latency of 1 ms or less and a transmissionreliability of 1E-9 or better. These techniques are based on the findingthat in MTC networks it is generally likely that event-triggered data isscheduled for transmitting less frequently than best-effort data; thisis particularly true if the grouping, as mentioned above, of UEs sharingradio resources depends on their capability of sending theevent-triggered data and the best-effort data, respectively. Thesetechniques are further based on the finding that in MTC networks 100allocation of strictly separate bandwidth to best-effort data on the onehand, and event-triggered data on the other hand is comparablyinefficient in terms of spectral efficiency; rather, re-using of radioresources allows increasing the spectral efficiency.

The techniques as illustrated in detail hereinafter rely onprioritization of scheduling of event-triggered data over best-effortdata. When a UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 requires tosend event-triggered data, transmission of, best-effort data and/orevent-triggered data by other UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2 of the MTC network 100 is blocked or muted. This allows freeingup the radio resources for the transmission of the event-triggered data.

According to various embodiments, the respective UE 101 a-1, 101 a-2,101 a-3, 101 b-1, 101 b-2 is configured to send a control message whichprospectively indicates the need to send a data packet of theevent-triggered data. E.g., this sending may be in response to the datapacket of the event-triggered data being scheduled for transmission in atransmit buffer of the respective UE 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2. This sending may alternatively or additionally be in responseto an event generating the event-triggered data occurring.

Generally, the control message may be sent on the channel. It is alsopossible that the control message is sent on the control channel.

The control message may be sent via the unicast transmission 180 to adedicated further UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 and/orto the access node 102. Alternatively or additionally, the controlmessage may be sent via the broadcast transmission 190. The controlmessage may be sent employing the control channel comprising dedicatedradio resources and/or may be sent employing the radio resources on thechannel reserved at least for the event-triggered data. E.g., if acontrol channel is employed, in case of the 3GPP LTE radio accesstechnology, the Physical UL Control Channel (PUCCH) may be employed.

The control message may further prompt the further UEs 101 a-1, 101 a-2,101 a-3, 101 b-1, 101 b-2 to mute transmission on the channel. Inparticular, the further UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2may thereby be prevented from sending best-effort data while the datapacket of the event-triggered data is being transmitted. Thus, itbecomes possible to share the radio resources on channel between the UEs101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 while a risk of collisionsmay be reduced.

Generally, the radio resources on the channel may be reserved solely tothe event-triggered data; however, it is also possible that the radioresources on the channel are reserved to the event-triggered data, aswell as to the best-effort data. If the radio resources on the channelare reserved solely to the event-triggered data, it may be possible thatfurther radio resources exist that are reserved for the best-effortdata, e.g., solely reserved for the best-effort data. Hence, it may bepossible that the radio resources on the channel shared between the UES101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 comprise distinct first andsecond radio resources; the first and second radio resources may bereserved for the event-triggered data and the best-effort data,respectively.

In any case, it may be possible that the UEs 101 a-1, 101 a-2, 101 a-3,101 b-1, 101 b-2 employ radio resources on the channel reserved for theevent-triggered data (first radio resources) for transmission of thebest-effort data, as well. In other words, the first radio resources maybe re-used for sending of data packets of the best-effort data. Thisallows reducing the latency for sending of the best-effort data.

Such a hybrid approach which relies on re-using resources allowscoexistence of the best-effort data and the event-triggered data on thechannel while fulfilling latency and reliability requirements. E.g., theUEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 may be configured tore-use the first radio resources for data packets of the best-effortdata in case of a high traffic load where, e.g., all available radioresources reserved for the best-effort data on the channel (second radioresources) are busy.

It is possible that the first radio resources are allocated to two ormore UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 in a shared manner.Alternatively or additionally, it is possible that the second radioresources are allocated to two or more UEs 101 a-1, 101 a-2, 101 a-3,101 b-1, 101 b-2 in a shared manner.

Generally, the second radio resources may be reserved as well.Generally, the second radio resources may be orthogonal in time and/orfrequency to further radio resources, e.g., radio resources on thecontrol channel and/or the first radio resources. Generally, the UEs 101a-1 101 b-1, 101 b-2 that are capable of sending the best-effort datamay be configured to select between the first radio resources and thesecond radio resources for sending of a data packet of the best-effortdata depending on a traffic load on the channel in the second radioresources. Then, the UEs 101 b-1, 101 b-2 may be configured to send thedata packet of the best-effort data employing the first radio resourcesif the first radio resources are selected. At the same time, however, ifthe control message prompts to mute transmission of the best-effortdata, this may be taken into account when selecting between the firstradio resources and the second radio resources as well. When judging thetraffic load, it is generally possible to take into consideration apredefined traffic threshold. If, e.g., the traffic on the channel fallsbelow the predefined traffic threshold, it is possible to rely on thesecond radio resources for sending of the data packet of the best-effortdata. E.g., in the exceptional circumstance that the traffic in thesecond radio resources exceeds the predefined traffic threshold, thefirst radio resources may be re-used for sending of the data packet ofthe best-effort data. This allows controlling re-usage of the firstradio resources for sending of best-effort traffic to the necessaryextent, i.e., as a fall-back solution. Thereby, collisions may beavoided.

In FIG. 2, the first radio resources 221 and the second radio resources222 are illustrated schematically over the course of time (horizontalaxis in FIG. 2) and frequency (vertical axis in FIG. 2) on the channel280. As can be seen from FIG. 2A, distinct radio resources 221, 222 areallocated for transmission of the event-triggered data and thebest-effort data. However, as mentioned above, if certain criteria aremet it is possible to re-use the first radio resources 221 for thetransmission of a data packet of the best-effort data.

Transmission on the channel 280 is subdivided in frames 211; if comparedto subframes of the 3GPP LTE scenario, the frames 211 may have a shorterduration of only 0.2 ms, i.e., scaled down by a factor of five. Frames211 may be scaled to by a larger factor, e.g., by a factor of ten. Eachframe 211 comprises a number of time-frequency resource blocks 215. Ascan be seen from FIG. 2, the first radio resources 221 are periodicallyreoccurring with a periodicity of P, namely every frame 211; the secondradio resources 222 are periodically reoccurring with a comparablylonger periodicity of P′, namely every second frame 211. The radioresources 221, 222 may, however, generally be reoccurring without astrict periodicity or following a certain distribution of periodicities.

Generally, it is even possible that a certain frequency band iscontiguously reserved for the event-triggered data and/or thebest-effort data, cf. FIG. 3.

In the scenario of FIG. 3, there are no distinct first and second radioresources 221, 222 reserved for the event-triggered data and thebest-effort data; instead, the radio resources 223 in the scenario ofFIG. 3, are allocated for transmission of, both, the best-effort dataand the event-triggered data. Such techniques may also be applied inscenarios according to FIG. 2.

Generally, the radio resources 221, 222, 223 may be prospectivelyallocated to the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2employing scheduling control messages transmitted from the access node102 to the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 in a downlink(DL) transmission. If there are distinct first radio resources 221 andsecond radio resources 222, there may be distinct scheduling controlmessages, as well.

The scheduling control messages may be sent on the channel and/or on thecontrol channel. The scheduling control messages may be sent via thebroadcast transmission 180 and/or via the unicast transmission 190.

The scheduling may be centrally controlled by the access node 102. Theaccess node 102 may send the scheduling control message(s) via theunicast transmission 190 and/or the broadcast transmission 180, e.g., inan initial set-up phase. For sending of the scheduling controlmessage(s), a DL control channel may be employed, e.g., in case of the3GPP LTE radio access technology the Physical DL Control Channel(PDDCH). Thus, the scheduling control message(s) may indicate thepre-scheduled or reserved radio resources.

The reservation of the first radio resources 221 and/or the second radioresources 222 may be accompanied by techniques of link adaptation toallocate appropriate time-frequency resources blocks 215 depending onthe conditions of the channel 280. The periodicity P, P′ of the radioresources 221, 222 typically depends on a traffic pattern and a validityof grants. The number of time-frequency resource blocks 215 may beadapted based on the conditions of the channel 280, an interferencepattern, etc. Generally, the amount of resources may be estimated onvarious parameters, e.g., a number of UEs 101 a-1, 101 a-2, 101 a-3, 101b-1, 101 b-2 connected to the MTC network 100; and/or a quality of thechannel 280 as reported by the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2; and/or a duration of a frame 111.

Thus, it is possible that the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2 are configured to receive, from the access node 102 via theunicast transmission 190 or the broadcast transmission 180, thescheduling control message which prospectively indicates at least partsof the radio resources 221, 222, e.g., the first radio resources 221and/or the second radio resources 222. Likewise, it is generallypossible that the access node 102 is configured to send, to one or moreUEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 via the unicasttransmission 190 or the broadcast transmission 180, said schedulingcontrol message.

In FIG. 4, a signalling diagram is shown. At 401, the access node 102sends in DL direction a first scheduling control message 471 to the UE101 a-1. The first scheduling control message 471 prospectivelyindicates the first radio resources 221. Then, at 402, the access node102 sends a second scheduling control message 472 to the UE 101 a-1. Thesecond scheduling control message 472 prospectively indicates the secondradio resources 222. In the scenario of FIG. 4, the scheduling controlmessages 471, 472 are sent via the unicast transmission 190. A DLcontrol channel is employed at 401, 402. Sending of the schedulingcontrol messages 471, 472 occurs in an initial set-up phase 490.

Then, some time after the initial set-up phase 490 has ended, the MTCnetwork 100 operates in a state where data transmission of data packetsof the event-triggered data and the best-effort data is generallypossible. At 403, first radio resources 221 that are reserved occur;yet, no data packets are actually sent. Again, at 410, the first radioresources 221 are not employed for transmission. Padding may beemployed.

Differently, at 404 a data packet 492 of best-effort data is sentemploying the second radio resources 222. Also at 406, 408, 409, 411data packets 492 of best-effort data are sent employing the second radioresources 222. At 404, 406, 408, 409, 411, UL transmission on thechannel 280 occurs via the unicast transmission 190.

At some point in time, an event 405 occurs. E.g., a warning may betriggered or some value of a PLC may cross a predefined threshold, etc.Thus, a data packet 491 of the event-triggered data is generated andeventually sent at 407 on the channel 280 via the unicast transmission190 to the access node 102 in the UL direction. E.g., the data packet491 may carry an emergency message or the like.

In the scenario of FIG. 4, the data packets 491 of the event-triggereddata and the data packets 492 of the best-effort data are sent via theunicast transmission 190 to the access node 102. Generally, the datapackets 491 and/or the data packets 492 could alternatively oradditionally be sent via the broadcast transmission 180 (not shown inFIG. 4).

As can be seen from the above, at 403 and 410, unused first radioresources 221 occur. The respective bandwidth is not used for payloaddata transmission. This is why at 403, 410 the UE 101 a-1 is configuredto check whether there is best-effort data to be transmitted; however,at 403, 410 the UE 101 a-1 determines that—while there may bebest-effort data to be transmitted, e.g., scheduled for transmission inan UL transmission buffer—the traffic load on the channel 280 in thesecond radio resources 222 is below a certain predefined trafficthreshold; thus the UE 101 a-1 selects the second radio resources 222for transmission of the data packets 492 of the best-effort data at 404and 411, respectively. Because of this, the otherwise unused first radioresources 221, 222 are not being re-used for transmission of thebest-effort data.

As can be seen from the above, in principle it is possible to re-use thefirst radio resources 221 for sending of best-effort data. This may be,however, selectively triggered depending on the traffic load on thesecond radio resources 222 as a fall-back solution.

The first radio resources 221 and the second radio resources 222 areshared between the UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2.Further, the first radio resources 221 may be re-used for transmissionof best-effort data. Thus, in a scenario as explained with respect toFIG. 4, collisions may occur. E.g., a situation may occur wherebest-effort data is sent employing the first radio resources 221 anotherUE 101 a-2, 101 a-3, 101 b-1, 101 b-2; at the same time, the UE 101 a-1may send the data packet 491 of the event-triggered data via thechannel. Thus, a collision may result. Techniques are described whichenable to reduce the likelihood of collisions.

Now referring to FIG. 5, a scenario is also conceivable where the UE 101a-1 or any other UE 101 a-2, 101 a-3, 101 b-1, 101 b-2 selects the firstradio resources 221 for sending of a data packet 492 of the best-effortdata and—at the same time—a likelihood of collisions is reduced. Thisoccurs by employing on a control message 580. The control message 580prospectively indicates the need of the UE 101 a-1 sending the datapacket 491 of the event-triggered data. Details of the techniques areexplained hereinafter.

Namely, at 503, a data packet 492 of the best-effort data is sentemploying the first radio resources 221. Here, the UE 101 a-1 selectsthe first radio resources 221 for transmission of the data packet 492 ofthe best-effort data, because the traffic load on the channel 280 in thesecond radio resources 222 is above the predefined traffic threshold. Inorder to ensure low-latency delivery of that data packet, the firstradio resources 221 are re-used—albeit in principle the first radioresources 221 are reserved for the transmission of the event-triggereddata.

Generally, different decision criteria are conceivable which may berelied upon when checking the traffic load on the channel 280 in thesecond radio resources 222. E.g., it may be possible to take intoaccount a size of the data packet 492 of the best-effort data which isto be transmitted; and/or a size of the second radio resources 222,e.g., within a certain time span; and/or a priority of the data includedin the data packet 492 of the best-effort data. E.g., if—within the timespan—the second radio resources 222 do not suffice to transmit the datapacket 492, given its determined size, then the fallback to the firstradio resources 221 may be executed. The time span may correlate with alatency requirement, e.g., according to QoS.

As can be seen from the above, the first radio resources 221 are, inprinciple, reserved for the event-triggered traffic. However, they canbe utilized for transmission of best-effort traffic as well in case of acongested network, e.g., due to high traffic load. Best-effortdata—typically corresponding to a lower transmission priority—isscheduled employing the first radio resources 221 in such a case; due tothe low priority of the best-effort data, such transmission can beblocked in case a data packet 491 of the event-triggered data needs tobe transmitted. This is achieved by means of the control message 580.

The control message 580 implements a collision avoidance mechanism. Thescenario of FIG. 5 corresponds to a D2D-assisted solution of thecollision avoidance mechanism to prioritize scheduling of data packets491 of the event-triggered data over data packets 492 of the best-effortdata. Because at 503 no control message 580 has been received by the UE101 a-1, the UE 101 a-1 is free to send the data packet 492 of thebest-effort data employing the first radio resources. In other words,selecting between the first radio resources 221 and second radioresources 222 generally may depend on whether or not the control message580 has been received.

In this regard, e.g. at 505, an event occurs and event-triggered data isgenerated. Thus, the UE 101 a-1 has event-triggered data to schedule forUL transmission; therefore, at 506, the UE 101 a-1 sends the controlmessage 580 which prospectively indicates the need of sending the datapacket 491 of the event-triggered data. The control message 580 is sentvia the broadcast transmission 180 to the remaining UEs 101 a-2, 101a-3, 101 b-1, 101 b-3 so that the remaining UEs 101 a-2, 101 a-3, 101b-1, 101 b-3 become aware of the presence of high-priorityevent-triggered traffic. Thus, the control message 580 prompts theremaining UEs 101 a-2, 101 a-3, 101 b-1, 101 b-3 to mute transmission onthe channel 280 employing the first radio resources 221. Generally, thecontrol message 580 may prompt muting of the transmission for a certainpredefined time period; and/or for a certain number of predefinedtime-frequency resource blocks 215; and/or for specifically indicatedtime-frequency resource blocks 215. Optionally, also the access node 102receives the control message 580 at 506 via the broadcast transmission180 and/or via the unicast transmission 190 (not shown in FIG. 5).

At 506, the control message 580 is sent via a control channel. However,generally it is also possible that the control message 580 is sent viathe channel 280.

Generally it is possible, but not mandatory, that the control message580 also includes explicit or implicit information about the specifictime-frequency resource block(s) 215 that the UE 101 a-1 intends to usefor transmission of the data packet 491 of the event-triggered data. Inparticular in such a scenario, the decision logic for selecting thetime-frequency resource block(s) 215 for transmission of the data packet491 may reside in the UE 101 a-1. Here, the UE 101 a-1 may take intoaccount information on the frame structure on the channel 280 and thequality of the channel 280. Thus, generally the control message 580 mayindicate the time-frequency resource block 215 of the first radioresources 221 and prompt the remaining UEs 101 a-2, 101 a-3, 101 b-1,101 b-3 to mute transmission in the indicated time-frequency resourceblock 215. Thus, generally it may be possible that the remaining UEs 101a-2, 101 a-3, 101 b-1, 101 b-3 are configured to select between thefirst radio resources 221 and the second radio resources 222 for sendingof a data packet 492 of the best-effort data depending on the indicatedtime-frequency resource block 215.

At 504, 507, 509, 510, 512 data packets 492 of the best-effort data areconventionally sent employing the second radio resources 222.

Above and with respect to 503, a scenario has been discussed where theUE 101 a-1 sends the data packet 492 of the best effort data employingthe first radio resources 221. Vice versa, because the first radioresources 221 are shared radio resources, it is also possible that oneor more of the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101 b-3 employthe first radio resources 221 for sending of data packets 592 of thebest-effort data. This occurs at 511.

As can be seen from FIG. 5, the UE 101 a-1 is capable of sending, both,the best-effort data and the event-triggered data. This may be generallyindicated in a capability control message 570. In the scenario of FIG.5, the UE 101 a-1 sends the capability control message 570 at 500, i.e.,during the set-up phase 490; sending occurs in UL direction, e.g.,employing the PUCCH. The capability control message 570 positivelyindicates the capability of the UE 101 a-1 to generate and send thebest-effort data and further positively indicates the capability of theUE 101 a-1 to generate and send the event-triggered data. Generally, itis also possible to rely on two distinct messages for signalling thecapability of generating and sending the best-effort data and the eventtriggered data, respectively.

The capability control message 570 is sent at 500 employing a dedicatedcontrol channel. Generally, the control message 570 may also be sent onthe channel 280.

While the capability control message 570 has been discussed withreference to FIG. 5 above, it is also possible to employ the capabilitycontrol message 570 in further embodiments.

In the scenario of FIG. 5, the data packets 491, 492 are sent via thebroadcast transmission 180; however, generally, the data packets 491,492 could be sent via the unicast transmission 190, e.g., selectively tothe access node 102 (cf. FIG. 4) or any other UE 101 a-2, 101 a-3, 101b-1, 101 b-2.

Likewise, in the scenario of FIG. 5, the control message 580 is sent viathe broadcast transmission 180. This facilitates the D2D-typeimplementation of the collision avoidance mechanism. Yet, generally itis also possible that the control message 580 is sent via the unicasttransmission 190; e.g., the control message may be directed to one ormore than one or all of the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101b-3 and/or the access node 102.

In FIG. 6, a further scenario is illustrated. 601 and 602 correspond to501 and 502, respectively. 603-607 correspond to 503-507, respectively;however, in the scenario of FIG. 6, the control message 580 does notindicate a time-frequency resource block 215 for the transmission of thedata packet 491 of the event-triggered data. This is because in thescenario of FIG. 6 the decision logic for scheduling the transmission ofthe data packet 491 of the event-triggered data does not reside withinthe UE 101 a-1, but in one of the further UEs 101 a-2, 101 a-3, 101 b-1,101 b-3 and/or the access node 102. A further control message 581 isreceived by the UE 101 a-1 at 608, e.g., from one of the further UEs 101a-2, 101 a-3, 101 b-1, 101 b-3 and/or the access node 102, after sendingof the control message 580; hence, the further control message 581 maybe referred to as a response message. The further control message 581can be generally sent via a dedicated control channel and/or via thechannel 280. This further control message 581 indicates thetime-frequency resource block 215 for sending of the data packet 491 ofthe event-triggered data. The further control message 581 prompts the UE101 a-1 to send the data packet 491 of the event-triggered dataemploying the indicated time-frequency resource block 215; the sendingoccurs at 609 employing the indicated time-frequency resource block 215of the first radio resources 221. Here, the UE 101 a-1 does not have toschedule sending of the data packet 491 of the event-triggered dataautonomously in the first radio resources 221; instead, the EU 101 a-1can rely on the time-frequency resource block 215 as indicated in thefurther control message 581. Here, the decision logic for scheduling thedata packet 491 of the event-triggered data resides, e.g., at the accessnode 201.

610-613 correspond to 509-512.

Generally, the decision logic for scheduling the data packet 491 of theevent-triggered data may be shared between the UE 101 a-1 and thefurther UEs 101 a-2, 101 a-3, 101 b-1, 101 b-3 and/or the access node102. E.g., the control message 580 may include a plurality of candidatetime-frequency resources blocks 215; then, the further control message581 may positively or negatively acknowledge the plurality of candidatetime-frequency resource blocks 215.

The scenario of FIG. 7 generally corresponds to the scenario of FIGS. 6.701 and 702 correspond to 601 and 602. However, different to FIG.6—which implements a D2D-assisted collision avoidance mechanism—in thescenario of FIG. 7, the collision avoidance mechanism is centrallyoperated by the access node 102.

At 703, a data packet 492 of the best-effort data is sent via theunicast transmission 190 by one of the remaining UEs 101 a-2, 101 a-3,101 b-1, 101 b-3; the corresponding first radio resources 221 areblocked by this transmission. If at 703, the UE 101 a-1 was to send adata packet 491 of the event-triggered data via the unicast transmission190 and/or the broadcast transmission 180 and employing the first radioresources 221, a collision would occur.

704 and 705 correspond to 604 and 605.

Differently to the scenario of FIG. 6, at 706 the control message 580 issent to the access node 102 via the unicast transmission 190. In thescenario of FIG. 7, the decision logic for scheduling the transmissionof the data packet 491 of the event-triggered data resides at the accessnode 102. Thus, the control message 580 at 706 is not required toinclude the indication of the time-frequency resource block 215 of thefirst radio resources 221 at which the transmission of the data packet491 is planned.

This indication of the time-frequency resource block 215 of the firstradio resources 221 at which the transmission of the data packet 491 isplanned is included in the further control message 581 sent from theaccess node 102 via the unicast transmission 190 to the UE 101 a-1 andadditionally sent to the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101b-3 via the broadcast transmission 180 or the unicast transmission 190.The further control message 581 prompts the remaining UEs 101 a-2, 101a-3, 101 b-1, 101 b-3 to mute transmission in the indicatedtime-frequency resource block 215. Sending of the further controlmessage 581 via the unicast transmission 190 to the UE 101 a-1 at 708 isoptionally; generally the further control message 581 may be sent to allUEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-3 via the broadcasttransmission 180.

710-714 correspond to 609-613.

As can be seen from the above—different to the D2D-assisted solution ofthe collision avoidance mechanism of, e.g., FIG. 6—, in the scenario ofFIG. 7 the access node 102 is involved in the scheduling.

Generally, the control message 580 and/or the further control message581 may be sent employing an UL/DL control channel. Here, collisions maybe avoided if the UL control channel and/or DL control channel does notinclude shared radio resources. Hence, if the UL control channel and/orDL control channel includes radio resources uniquely allocated to one ofthe UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2, collisions may beavoided; this is typically the case for the unicast transmission 190. Inscenarios where the control message 580 is sent employing shared radioresources—e.g., on a D2D-broadcast control channel or on the channel 280via the radio resources 221, 222, 223—, it may be feasible to implementa collision-avoidance technique. Generally, it is possible that aChannel Sense Multiple Access with Collision Detection (CSMA/CD)technique is employed for the transmission of the control messages 580,581. In particular, when a propagation time of the MTC network 100 iscomparably small, a high efficiency of the CSMA/CD technique may beachieved; e.g., the efficiency may approach 100%.

A collision of two control messages 580, 581 sent by different UEs 101a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 via shared radio resources on acontrol channel is shown in FIG. 8, at 806 a, 806 b. In FIG. 8, 801-804correspond to 601-604. At 805 a and 805 b events occur at the UE 101 a-1and a given one of the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101 b-3,respectively, which events generate event-triggered data. The UE 101 a-1and the given one of the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101b-3 send the control message 580 via the broadcast transmission 180; acollision occurs as the control channel is shared between the UE 101 a-1and the given one of the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101b-3. According to the CSMA/CD technique, the UE 101 a-1 re-transmits thecontrol message 580 some random time later at 808; also the given one ofthe remaining UEs 101 a-2, 101 a-3, 101 b-1, 101 b-3 re-transmits thecontrol message 580 some random time later at 811. Thereby, thecollision is resolved. The control message 580 re-transmitted at 808indicates the time-frequency resource block 215 for transmission of thedata packet 491 at 809 employing the first radio resources. The controlmessage 580 sent at 811 indicates the time-frequency resource block 215for transmission of the data packet 491 at 812.

At 807, 810, 813 data packets 492 of the best-effort data aretransmitted employing the second radio resources 222.

Above, with reference to FIGS. 4-8, scenarios have been discussed wherethere are first radio resources 221 dedicated primarily to transmittingof the event-triggered data and where there are second radio resources222 dedicated primarily to transmitting of the best-effort data. In FIG.9, a scenario is illustrated where there are no dedicated first andsecond radio resources 221, 222; instead, the radio resources 223 arereserved for, both, the event-triggered data and the best-effort data.

900-902 correspond to 500-502. Further, 903-912 correspond to 503-512where, however, the radio resources 223 are employed for sending of thedata packets 491, 492 of, both, the event-triggered data and thebest-effort data.

FIG. 10 is a signalling diagram illustrating wireless transmissionbetween the UE 101 a-1 and the UE 101 b-1. According to the techniquesas described herein, new event-triggered data is available at a transmitbuffer of the UE 101 a-1 at 1001. At 1002, channel contention of acontrol channel 281 occurs: Because the UE 101 a-1 has the correspondingdata packet 491 of the event-triggered data scheduled for ULtransmission, the UE 101 a-1 senses the control channel 281, inparticular those time-frequency resources 215 associated with thebroadcast transmission 180. If the control channel 281 is idle, i.e.,the remaining UEs 101 a-2, 101 a-3, 101 b-1, 101 b-3 are nottransmitting, the UE 101 a-1 broadcasts the control message 580 at 1003via the broadcast transmission 180 on the control channel 281. Thecontrol message 580 is received by the remaining UEs 101 a-2, 101 a-3,101 b-1, 101 b-3, i.e., in particular by UE 101 a-2 at 1004. The UE 101a-2 decodes the control message 580. It thereby retrieves the indicationof the time-frequency resource block 215 which the UE 101 a-1 employsfor sending the data packet 491 on the channel 280 at 1007. The UE 101b-1 mutes transmission in this time-frequency resource block 215 at 1006in the respective radio resources 221, 222, 223 on the channel 280. Inparticular, if the UE 101 b-1 is capable of sending best-effort data, itblocks the best-effort data at this time-frequency resource block 215 onthe channel 280 to allow the transmission of the data packet 491 by theUE 101 a-1.

A scenario may occur where the control channel 281 is sensed to be busyat 1002. A reason for this may be that at 1002 the UE 101 a-2 sends acontrol message 580. If this happens, the UE 101 a-1 goes to back-offmechanism. An exponential back-off mechanism may be employedcorresponding to the CSMA/CD techniques.

A further scenario is shown in FIG. 11. Here, both the UE 101 a-1 aswell as the UE 101 a-2 sense that the control channel 281 is idle at1103. The control channel 281 comprises shared radio resources. Then,both the UE 101 a-1 as well as the UE 101 a-2 send—employing the sameshared radio resources on the control channel 281—a respective controlmessage 580 at 1104, 1105, respectively, the control messages 580indicating the need of the UEs 101 a-1, 101 a-2 of sending a data packet491 of the event-triggered data having arrived at the respective ULtransmit buffer at 1101, 1102, respectively. The UE 101 a-1 detects thecollision, e.g., by measuring energy levels during 1106. The UE 101 a-1may block the broadcast transmission 180 and go to exponential back-off.The UE 101 a-2 may act accordingly. Both UEs 101 a-1, 101 a-2 implementrandom back-off periods 1109, 1111 which avoids collision whenre-sending the control messages 580 at 1112, 1113. Thus, the controlmessages 580 may be finally successfully received at 1113, 1115,respectively.

The detecting of the collision may involve sensing the signal level onthe control channel 281 in response to sending the control message 580.A threshold comparison between the sensed signal level and a predefinedsignal threshold may be executed. Depending on the threshold comparison,the control message 580 may be selectively re-sent.

In FIG. 12, a scenario is shown which does not rely on the D2D-assistedcollision avoidance mechanism. Here, at 1201 event-triggered dataarrives at a transmit buffer of the UE 101 a-1. After optional channelcontention (not shown in FIG. 12), the UE 101 a-1 sends the controlmessage 580 via the unicast transmission 190 to the access node 102 at1203. The dedicated UL control channel 281 may be employed; e.g., the ULcontrol channel 281 may not comprise shared radio resources renderingchannel contention unnecessary. The access node 102 receives the controlmessage 580 at 1204. After some processing delay 1205, the access node102 sends the further control message 581 via the unicast transmission190 to the UE 101 a-1 at 1206. A dedicated DL control channel 281 may beemployed; e.g., the DL control channel 281 may not comprise shared radioresources rendering channel contention unnecessary. The UE 101 a-1receives the further control message 581 at 1207. After some processingdelay at 1208, the UE 101 a-1 sends the data packet 491 at thetime-frequency resource block(s) 215 indicated by the further controlmessage 581.

In the scenario of FIG. 12, the latency may be assumed to correspond tothree times the transmission time and two times the processing delay;this may amount to approximately three times a duration of a frame 211plus additional time for data processing (processing delay). Here, theaccess node 102 sends the further control message 581 in the nextavailable frame 211 after 1204 and the UE 101 a-1 sends the data packet491 in the next available frame 211 after 1107, i.e., the processingdelay 1205, 1208 can be less than the duration of a frame 211. Thetransmission of the data packet 491 is scheduled in the third frame 211after 1203. Where the duration of the frame 211 amounts to, e.g., 0.2milliseconds, the total time between 1201 and 1209 (latency) amounts toapproximately 0.6 milliseconds.

FIG. 13 is a flowchart of a method according to various embodiments. At1301, information indicating the radio resources 221, 222, 223 isstored. E.g., the information can indicate the first radio resources 221and/or the second radio resources 222. The first radio resources 221and/or the second radio resources 223 may be shared between the variousUEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2. It is also possiblethat the radio resources 223 are not distinctly allocated to theevent-triggered data and the best-effort data, but are reserved for,both, the event-triggered data and the best-effort data.

At 1302, the control message 580, 581 is received. The control message580, 581 may be received via the control channel 281 and/or the channel280 via at least one of the broadcast transmission 180 and the unicasttransmission 190. The control message 580, 581 prospectively indicatesthe time-frequency resource block 215 of the radio resources 221, 222,223.

The control message 580, 581 prompts the respective UE 101 a-1, 101 a-2,101 a-3, 101 b-1, 101 b-2 to mute transmission in the indicatedtime-frequency resource block 215 at 1303. Thus, the collision avoidancemechanism may be implemented. If the control message 580, 581 isreceived from a further UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101b-2—e.g., via the broadcast transmission 180 on the control channel281—, a D2D-assisted collision avoidance mechanism may be implemented.The control message 580, 581 may also be received from the access node102.

Optionally, the respective UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101b-2 may send a data packet 491, 492 of the event-triggered data and/orthe best-effort data via the radio resources 221, 222, 223 at anothertime-frequency resource block 215 than the one indicated by the controlmessage 580 (not shown in FIG. 13).

FIG. 14 is a flowchart according to various embodiments. At 1401,information indicating the first radio resources 221 and the secondradio resources 222 is stored at a memory.

The first radio resources 221 of the channel 280 are reserved for theevent-triggered data; the second radio resources 222 of the channel 280are reserved for the best-effort data. The first and second radioresources 221, 222 are shared radio resources. At 1402, the informationis retrieved from the memory. Then, selecting between the first radioresources 221 and the second radio resources 222 occurs for sending of adata packet 492 of the best-effort data. 1402 may be in response to thedata packet 492 becoming available in an UL transmit buffer.

At 1402, different decision criteria can be taken into account for saidselecting between the first radio resources 221 and the second radioresources 222. E.g., it is possible that said selecting depends on atraffic load of the channel 280 in the second radio resources 222.Alternatively or additionally, said selecting may depend on whether acontrol message 580, 581 has been received, said control message 580,581 prompting to mute transmission on the channel 280. Alternatively oradditionally, said selecting may depend on the time-frequency resourceblock 215 which is indicated by said control message 580, 581 previouslyreceived.

E.g., the traffic load may be determined. Determining the traffic loadin the second radio resource 222 may comprise executing a thresholdcomparison between the determined traffic load and a predefined trafficthreshold. It is possible that the first radio resources 222 areselected at 1402 if said threshold comparison between the determinedtraffic load and a predefined traffic threshold yields that the trafficload falls below the predefined traffic threshold.

At 1403, it is checked whether the first radio resources have beenselected at 1402. If this is the case, at 1404, the data packet 492 ofthe best-effort data is sent employing the first radio resources 221.Thus, it is possible to re-use the first radio resources 221—which hadbeen originally reserved further event-triggered data—for said sendingof the data packet 492 of the best-effort data.

If, at 1403 it is judged that the second radio resources 222 have beenselected at 1402, the method may optionally include sending of the datapacket 492 of the best-effort data employing the second radio resources222 (not shown in FIG. 14).

FIG. 15 is a flowchart of a method according to various embodiments. At1501, information indicating the radio resources 221, 222, 223 is storedin a memory. The radio resources 221, 222, 223 are reserved at least forthe event-triggered data. Additionally, it is also possible that theradio resources 221, 222, 223 are reserved for the best-effort data.E.g., at 1501, it is possible to store information which indicates thefirst radio resources 221 being reserved for the event-triggered dataand the second radio resources 222 being reserved for the best-effortdata.

At 1502, it is checked whether a need for sending a data packet 491 ofthe event-triggered data and employing the radio resources 221, 222, 223exists. E.g., at 1502, it is possible to check whether a data packet 491of the event-triggered data is pending for transmission in an ULtransmit buffer of the respective UE 101 a-1, 101 a-2, 101 a-3, 101 b-1,101 b-2.

If at 1502 it is judged that the need for sending the data packets 491exists, the method commences with 1503. At 1503, the control message 580is sent. The control message 580 prospectively indicates the need ofsending the data packet 491.

Generally, it is possible to employ different techniques of sending thecontrol messages 580 at 1503. E.g., it is possible that at 1503, thecontrol message 580 is sent via the broadcast transmission 180 to anyfurther UEs and/or to the access node 102. Alternatively or additionallyat 1503, the control message 580 may be sent via the unicasttransmission 190 to the access node 102. Generally, it is possible thatthe control message 580 is sent via the channel 280 on which the radioresources 221, 222, 223 reside; alternatively or additionally, thecontrol message 580 may be sent on the control channel 281.

Further, the content of the control message 580 sent at 1503 may differin various scenarios. In one scenario, the control message 1503 mayimplicitly or explicitly indicate the need for sending the data packet491, e.g., without specifying a particular time-frequency resource block215 which is envisioned for said sending of the control message 580. Inother scenarios, it is possible that the control message 580 explicitlyor implicitly indicates one or more particular time-frequency resourceblocks 215 for which sending of the control message 580 is scheduled.E.g., it is possible that the control message 580 indicates a pluralityof candidate time-frequency resource blocks 215.

Depending on a further control message 581 received after sending of thecontrol message 580 and positively or negatively acknowledging theplurality of candidate time-frequency resource blocks 215, one or moreof the candidate time slots may be specifically selected for saidsending of the control message 580.

At 1504, the data packet 591 of the event-triggered data is sentemploying the radio resources 221, 222, 223. In particular, in 1504 itis possible that the data packet 491 is sent in the particulartime-frequency resource block 215 which has been indicated by thecontrol message 580 sent at 1503. Alternatively or additionally, at 1504the data packet 491 can be sent in the time-frequency resource block 250which has been indicated by a further control message (not shown in FIG.15) which has been received after said sending the control message 580at 1503.

As can be seen from the above, it is possible that the decision logicfor selecting the particular time-frequency resource block 215 which isused for said sending control message 580 fully or partly resides in therespective UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 which sendsthe data packet 491 at 1504. Likewise, according to various scenarios itis possible that this decision logic of selecting the time-frequencyresource block 215 used for said sending of the data packets 491 fullyor partly resides within the access node 102 and/or one of the furtherUEs.

In FIG. 16, the method according to various embodiments is illustratedin a flowchart. At 1601, the radio resources 221, 222, 223 areprospectively allocated to a UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101b-2 and to a further UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 in ashared manner. E.g., at 1601, it is possible to prospectively allocatefirst radio resources 221 reserved for the event-triggered data and/orprospectively allocate the second radio resources 222 reserved for thebest-effort data. Generally, the radio resources 221, 222, 223 that areprospectively allocated at 1501 can be reoccurring radio resources.

At 1602, the control message 580 is received. The control message 580prospectively indicates the need of a given UE 101 a-1, 101 a-2, 101a-3, 101 b-1, 101 b-2 sending the data packet 491 of the event-triggereddata.

Then, at 1603, the time-frequency resource block 250 of the radioresources for sending of the data packets 491 is selected.

At 1604, the further control message 581 indicating the selectedtime-frequency resource block 215 of the radio resources 221, 222, 223is sent. The further control message 581 may be sent on the controlchannel 581 and/or the channel 580 via at least one of the broadcasttransmission 180 and/or the unicast transmission.

E.g., the method according to FIG. 16 can be executed by the access node202. In such a scenario, it is possible that the decision logic forselecting the time-frequency resource block 215 at 1603 resides at leastpartly within the access node 102. E.g., it is possible that the controlmessage 580 received at 1602 indicates a plurality of candidatetime-frequency resource blocks 215. Then, at 1503, a particulartime-frequency resource block 215 may be selected from the plurality ofcandidate time-frequency resource blocks 215 indicated by the controlmessage 580. It is possible that the further control message 581positively and/or negatively indicates at least some of the candidatetime-frequency resource blocks 215 indicated by the control message 580.

FIG. 17 schematically illustrates the UEs 101 a-1, 101 a-2, 101 a-3, 101b-1, 101 b-2. The UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2comprise a processor 1701. The processor 1701 may be a multi-coreprocessor; alternatively or additionally, distributed computing may berelied upon. The UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2 furthercomprise a wireless interface 1702. The wireless interface 1702 may alsobe referred to as a radio interface. The wireless interface 1702 isconfigured to wirelessly transceive data on the channel 280 and thecontrol channel 281 of the MTC network 100. Generally, the UL controlchannel 281 may correspond to the PUCCH in case of the 3GPP LTE radioaccess technology. Likewise, the DL control channel 281 may generallycorrespond to the PDCCH in case of the 3GPP LTE radio access technology.Hence, the wireless interface 1702 may support, both, UL and DLtransmission. The UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2further comprise a human-machine interface (HMI) 1703. E.g., the HMI1703 may comprise one or more of the following: a keyboard, atouch-sensitive display, a display, a button, a loudspeaker, a speechrecognition system, etc. The UEs 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101b-2 further comprise a memory 1704, e.g., a non-volatile memory. Thememory 1704 stores control instructions which, when executed by theprocessor 1701, cause the respective UE 101 a-1, 101 a-2, 101 a-3, 101b-1, 101 b-2 to perform techniques according to FIGS. 13-15. The memory1704 may further store information regarding the radio resources 221,222, 223. This is possible because the radio resources 221, 222, 223 arereserved.

FIG. 18 schematically illustrates the access node 102. The access node102 comprises a processor 1801. The processor 1801 may be a multi-coreprocessor. Alternatively or additionally, distributed computing may berelied upon. The access node 102 further comprises a wireless interface1802. The wireless interface 1802 may also be referred to as a radiointerface. The wireless interface 1802 is configured to wirelesslytransceive data on the channel 280 of the MTC network 100 and thecontrol channel 281 of the MTC network 100. Generally, the UL controlchannel 281 may correspond to the PUCCH in case of the 3GPP LTE radioaccess technology. Likewise, the DL control channel 281 may generallycorrespond to the PDCCH in case of the 3GPP LTE radio access technology.Hence, the wireless interface 1802 may support both UL and DLtransmission. The access node 102 further comprises a HMI 1803. E.g.,the HMI 1803 may comprise one or more of the following: a keyboard, atouch-sensitive display, a display, a button, a loudspeaker, a speechrecognition system, etc. The access node 102 further comprises a memory1804, e.g., a non-volatile memory. The memory 1804 stores controlinstructions, which, when executed by the processor 1801 causes theaccess node 102 to perform techniques according to FIG. 16. The memory1804 may further store information regarding the radio resources 221,222, 223. This is possible because the radio resources 221, 222, 223 arereserved, respectively prospectively allocated by the access node 102.

FIG. 19 is a flowchart of a method according to various embodiments. At1901, a data packet 492 of the best-effort data is received at atransmit buffer of a given UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101b-2. At 1902, it is checked whether the traffic load in the second radioresources 222 is high. E.g., as part of 1902, it is possible todetermine the traffic load in the second radio resources and compare thedetermined traffic load with a predefined traffic threshold.

If at 1902 it is determined that the traffic load in the second radioresources 222 is not high, the data packet 492 of the best-effort datareceived at 1901 is sent employing the second resources 222 in 1903.

If, however, at 1902 it is judged that the traffic load of the secondradio resources is comparably high, it is checked at 1904 whether acontrol message 580, 581 has been previously received. If the controlmessage 580, 581 has not been received, the data packet 492 of thebest-effort data is sent employing the first radio resources 221 at1905. If, however, at 1904 it is judged that the control message 580,581 has been previously received, the transmission in first radioresources 221 is muted for a predefined time period at 1905 and/or inthe indicated time-frequency resource block(s) 215.

In FIG. 20, a flowchart of a method according to various embodiments isillustrated. At 2001, an event occurs. Because of this, a data packet491 of the event-triggered data is received in a transmit buffer of therespective UE 101 a-1, 101 a-2, 101 a-3, 101 b-1, 101 b-2.

Receiving the data packet 491 triggers sending of the control message580 at 2002. The control message 580 may optionally indicate a specifictime-frequency resource block 250 or a plurality of candidatetime-frequency resource blocks intended for sending of the data packet491.

At 2003, it is checked whether while sending the control message 580 at2002, a collision with a further device transmitting on the channel 280has occurred. If at 2003 a collision is detected, the method commencesat 2004. At 2004, the UE goes to back-off. I.e., the UE waits for arandom back-off period according to a CSMA/CD technique. Then, at 2005,the control message 480 is re-sent and the method commences at 2006.

If, however, at 2003 no collision is detected, the method commencesdirectly at 2006. At 2006, optionally, the further control message 581is received. E.g., if the control message 580 includes a plurality ofcandidate time-frequency resource blocks, the further control message581 may positively or negatively acknowledge the plurality of candidatetime-frequency resource blocks 215. It is also possible that the furthercontrol message 581 indicates a single time-frequency resource block215, e.g., if the control message 580 does not indicate anytime-frequency resource block 215.

AT 2007, the data packet 491 of the event-triggered data is sentemploying the time-frequency resource block 215.

In FIG. 21, the control message 580 and the further control message 581are illustrated. The control message 580 includes an indication of theparticular time-frequency resource block 215 which is intended forsending of the data packet 491 of the event-triggered data. In thescenario of FIG. 21, the particular time-frequency resource block 215 isrelatively defined with respect to a reference subframe 211.

In the scenario of FIG. 21, the further control message 580 positivelyacknowledges that the time-frequency resource block 215 is indicated bythe control message 580.

Likewise, it would be possible that the further control message 581negatively acknowledges that the time-frequency resource block 215 isindicated by the control message 580. Then it might be possible topropose a different time-frequency resource block for said sending ofthe data packet 491 of the event-triggered data.

In FIG. 22, the control message 580 and the further control message 581are illustrated according to various embodiments. In the scenario ofFIG. 2, the control message 580 does not include an indication of thetime-frequency resource block 215; rather, the control message 580explicitly indicates the need to send the data packet 491 of theevent-triggered data. It would be possible that the need of sending thedata packets 491 of the event-triggered data is implicitly indicated bythe control message 580.

The further control message 581 in the scenario of FIG. 22 includes theindication of the time-frequency resource block 215.

Generally, it may be possible that the control message 580 and/or thefurther control message 581 indicate a plurality of time-frequencyresource blocks 215.

Summarizing, above techniques have been shown which enable to re-useresources reserved at least for a first class of data for thetransmission of a second class of data. A D2D-assisted collisionavoidance mechanism is possible where the various UE pre-emptivelybroadcast a need for sending a data packet of the first class of data.Other scenarios do not rely on the D2D-assisted collision avoidancemechanism: E.g., when an access node of a wireless network gets anindication of one of a given UE that it needs to send a data packet ofthe first class of data, the access node can send a control message tothe remaining UEs to free-up radio resources for sending of that datapacket. Along with this, the access node may indicate which part ortime-frequency resource block of the radio resources should be used bythe requesting UE; it is also possible that the requesting UEautonomously picks one or few time-frequency resource blocks to transmitthe data packet of the first class of data. Said picking may be based onreliability requirements, QoS requirements, and/or channel conditions.

Although the invention has been shown and described with respect tocertain preferred embodiments, equivalents and modifications will occurto others skilled in the art upon the reading and understanding of thespecification. The present invention includes all such equivalents andmodifications and is limited only by the scope of the appended claims.

E.g., above reference has been primarily made to two specific classes ofdata, i.e., the event-triggered data and the best-effort data. Yet, ingeneral it is possible that different types of data are subject totechniques as illustrated above. Techniques as illustrated above can bereadily applied to any two classes of data, i.e., a first class of dataand a second class of data. E.g., the first class of data and the secondclass of data may be characterized in terms of different transmissionpriority or the like.

It may also be possible that the control message includes an indicationof the priority of the data packet of the event-triggered data to betransmitted. Then, if further UEs have lower priority event-triggereddata to be transmitted, the further UEs may postpone the transmission,i.e., execute backoff.

While above various embodiments have been discussed in view of sendingof data packets via the broadcast transmission or the unicasttransmission, it is generally possible to send the data packets via anyof the broadcast and unicast transmission. Likewise, sending of controlmessages may occur via unicast transmission or broadcast transmission;and optionally employ a dedicated control channel. It is not necessarythat the control channel comprises shared radio resources.

While above various embodiments have been discussed primarily withrespect to the MTC network, generally such techniques may be readilyapplied to other kinds of networks. In particular, such techniques maybe applied to a cellular network.

1. A communication device, comprising: a wireless interface configuredto transceive data on a channel of a wireless network, a memoryconfigured to store information indicating first radio resources on thechannel reserved for a first class of data and second radio resources onthe channel reserved for a second class of data, the first radioresources and the second radio resources being shared between thecommunication device and a further communication device, and at leastone processor configured to: transmit, via the wireless interface, thesecond class of data employing the first radio resources reserved forthe first class of data while traffic load of the channel for the secondradio resources is above a threshold, the first class of data havingpriority over the second class of data; responsive to receiving a firstcontrol message transmitted from the further communication device, thefirst control message prospectively indicating a need of sending a datapacket of the first class of data employing the first radio resources,mute transmission of the sending of the second class of data employingthe first radio resources while the data packet of the first class ofdata is being transmitted by the further communication device;responsive to the data packet of the first class being transmitted,resume transmitting the second class of data employing the first radioresources reserved for the first class of data while the traffic load ofthe channel for the second radio resources is above the threshold;transmit, via the wireless interface, a second control message, saidsecond control message prospectively indicating a need of sending a datapacket of the first class of data employing the first radio resources,wherein the second control message prompts the further communicationdevice to mute transmission to prevent the second class of data to besent on the channel reserved for the first class of data while the datapacket of the first class of data is being sent; stop transmitting thesecond class of data employing the first radio resources to transmit thedata packet of the first class of data; transmit, via the wirelessinterface on the channel, the data packet of the first class of dataemploying the first radio resources; resume transmitting the secondclass of data employing the first radio resources reserved for the firstclass of data while the traffic load of the channel for the second radioresources is above the threshold; and repeat the steps to mutetransmission and resume transmission responsive to receiving a furtherfirst control message.
 2. A communication device, comprising: a wirelessinterface configured to transceive data on a channel of a wirelessnetwork, a memory configured to store information indicating first radioresources on the channel reserved for a first class of data and secondradio resources on the channel reserved for a second class of data, thefirst radio resources and the second radio resources being sharedbetween the communication device and a further communication device, andat least one processor configured to: transmit, via the wirelessinterface, the second class of data employing the first radio resourcesreserved for the first class of data while traffic load of the channelfor the second radio resources is above a threshold, the first class ofdata having priority over the second class of data; responsive toreceiving a first control message transmitted from the furthercommunication device, the first control message prospectively indicatinga need of sending a data packet of the first class of data employing thefirst radio resources, mute transmission of the sending of the secondclass of data employing the first radio resources while the data packetof the first class of data is being transmitted by the furthercommunication device; responsive to the data packet of the first classbeing transmitted, resume transmitting the second class of dataemploying the first radio resources reserved for the first class of datawhile the traffic load of the channel for the second radio resources isabove the threshold; and transmit, via the wireless interface, a secondcontrol message, said second control message prospectively indicating aneed of sending a data packet of the first class of data employing thefirst radio resources, wherein the second control message prompts thefurther communication device to mute transmission to prevent the secondclass of data to be sent on the channel reserved for the first class ofdata while the data packet of the first class of data is being sent.